Calibration Log
A calibration log is a document that records temperature readings during thermometer calibration testing, along with corrective actions taken to resolve inaccuracies, serving as proof that thermometers are accurate and regularly tested for health inspection compliance.
A calibration log is a document that records temperature readings during thermometer testing, along with any corrective actions taken to fix inaccuracies. These logs prove to health inspectors that your thermometers are accurate and regularly tested, making your temperature readings trustworthy during inspections.
What Goes in a Calibration Log
Every calibration log entry should include the date and time of calibration, the target temperature (32°F or 212°F), the actual reading from your thermometer, and any adjustments made. Also record the thermometer model or ID number, the calibration method used (ice point or boiling point), and staff initials or signature.
When a thermometer can’t be adjusted to match the standard temperature, note the replacement in the log. If temperature drift consistently exceeds ±2°F (±0.5°C), it’s time for a new thermometer—no amount of calibration will fix that.
Calibration Methods and Frequency
The ice point method uses an ice water slurry at 32°F (0°C) and works best for thermometers used with cold foods. The boiling point method uses boiling water at 212°F (100°C at sea level, adjusted for altitude), but requires caution to prevent burns.
Food-contact probe thermometers need daily calibration at the start of each shift. Refrigerator and freezer thermometers can be checked monthly. Always calibrate after dropping a thermometer or exposing it to extreme temperature changes—the impact can throw off accuracy.
Why Health Inspectors Care
Health departments review calibration logs during inspections as part of HACCP compliance verification. Without documented proof that your thermometers are accurate, inspectors can’t trust your temperature logs. This matters especially for monitoring the danger zone and maintaining proper time-temperature control of TCS foods.
The FDA Food Code recommends regular thermometer calibration, and many states require it as part of their food safety plans. During a health inspection, calibration logs demonstrate that temperature monitoring at critical control points is backed by reliable equipment.
Paper vs. Digital Systems
Traditional paper logs work fine, but digital systems are gaining ground in commercial kitchens. Digital calibration logs offer automated time-stamping, corrective action workflows, and easier access during audits. They also reduce the risk of lost paperwork or illegible handwriting that can complicate inspections.
Whether you use paper or software, consistency matters more than format. Keep logs accessible for at least 90 days, though many operations retain them longer to track equipment performance trends and justify replacement decisions.
Common Uses
Calibration logs are reviewed at the start of every shift when food-contact thermometers are calibrated. Kitchen managers sign off on daily entries before service begins. Health inspectors request these logs during routine inspections to verify HACCP compliance and validate temperature monitoring procedures. When thermometers malfunction or show inconsistent readings, staff reference calibration logs to identify patterns and determine if replacement is needed. Digital systems automatically timestamp entries and flag missed calibrations, making them increasingly common in chain restaurants and larger operations.